Telephone system



Jan. 3, 1939.

,H. TPFER TELEPHONE SYSTEM Filed Sept. 11, 1956 2 Sheets-Sheet 1 N w;in, in 4 W was 1/ D3 %5 mmN. mfimw mfiww m 4 Ag W m Em 5:? m2

INVENTORQ RBERT TOPFEBI ATTORNEY.

Jan. 3, 1939. H T PFER 2,142,663

TELEPHONE SYSTEM Filed Sept. l l, 1956 2 Sheets-Sheet 2 HERBERT TOPFERATTORNEY.

Patented Jan. 3, 1939 UNITED STAT car if NT OFFICE TELEPHONE SYSTEMApplication September 11, 1936, Serial No. 100,250 In Germany September16, 1935 12 Claims.

The present invention relates to a circuit arrangement for remotecommunication systems and more especially to telephone systems foreffecting two different speaking operations over the same lead. It aimsat effecting the switching operations in a manner which is always sureand free from objections with the minimum of additional auxiliarydevices,.and also at maintaining the one switching operation whilepromo-ting the second switching operation.

The present invention affords special advantages in cases where over theone lead a con.- nection is being held, for example an outgoing line,and another switching operation, for example metering, is to beeffected.

A further advantage of the invention consists in that the newarrangement can be used without difliculty in systems already in:existence since in this case the carrying out of all the switchingoperations is facilitated without considerably affecting the existingsystem merely by incorporating the necessary receiving devices andrectifiers for effecting the new switching operation.

The invention: consists in that a rectifier is arranged in parallel witheach of the two magnets which are connected in series and effect theswitching operations, which rectifiers are arranged in the opposite.sense with respect to one another, one of the operations being effectedwithout disturbing the first by means of alternating current.

Embodiments of the invention are shown in the drawings. The arrangementaccording to Fig. 1 relates to metering, in point of fact time metering,while the call is in progress.

In Fig. 2 another embodiment is represented in which definite signalsare transmitted to a particular position during the establishment of acall by the arrangement according to the invention.

Fig. 3 shows an arrangement in which routing over a particular traflicdirection is effected by means of the invention.

The detailed arrangements will now be described: In the interest ofsimplicity and clarity only those details which are necessary forexplaining the invention are shown.

When the subscriber In in the arrangement according to Fig. l raises hisreceiver for the purpose of establishing a call the following circuit isset up: earth, winding of relay R, contact It, subscribers loop, contact3t, resistance Wil, battery and earth. Relay R energizing in this circuit closes its contact 81 and thereby completes the following circuitfor the rotary magnet D of the pr-eselector VW: earth, battery, contacts81' and 6t, rotary magnet D, relay interrupter RU and earth. When thepreselector has found a free first group selector IGW the followingtesting circuit is established: earth, battery, contact 5 l7, windingsII and I of relay T (in parallel with winding I of the meter relay Zwhich, however, does not energize in'this circuit), wiper C of thepreselector VW, resistance Wi3, winding of relay 0, off-normal contactlZk, of the preselector (op- 10 erated after the first vertical step)and earth, and in parallel over contact Kim of the release magnet of thegroup selector IGW and resistance W24 and earth. In this circuit relaysT and C energize. On account of the closing of contact 5t 15 the highresistance winding II of relay T is shortcircuited and thereby the groupselector which has been seized is guarded against further seizure. Bythe opening of contact 6t the preselector is brought to rest. Atcontacts It and 415 the line of 20 subscriber In is switched through tothe first group selector IGW. The following circuit exists for relay Ainthe first group selector IGW: earth, battery, winding of relay A,wiper a, of the preselector VW, contact It, subscribers loop, 25.contact it, wiper b of the. preselector VW, resistance WW2, and earth.The first group selector IGW is now set in the known way by the callingsubscriber, in that the impulse relay A transmits a number of impulses,corresponding to the digit 3 transmitted, to the vertical magnet of thefirst group selector IGW. When the switch has been set on the desiredlevel it searches to find a free second group selector IIGW. When thisis found the following circuit is established: earth, battery, 35resistance W 'S, winding II of relay 0 I off-normal contact 23k! (openafter the first vertical step of the second group selector), contactl8zr2, wiper c' of the first group selector IGW, winding I of relay P(whose short-circuit is removed by con- 40 tact hie), winding II ofrelay P, contact I and earth. In this circuit the testing relay P of thefirst group selector IGW and the seizing relay CI of the second groupselector both energize. Current from the circuit thus mentioned cannotbe 45 transmitted through the rectifier Gll arranged in parallel withwinding I of relay P since it is nonconductive to current in thisdirection. Relay P closes contact i510 thereby establishing ashortcircuit over the high resistance winding II of re- 50 lay P so thatthe seized second group selector IIGW is guarded against furtherseizure. The guarding circuit passes from contact I520 over therectifier G12 to earth. The rectifier G12 is connected up in theopposite sense to rectifier GI] and is conductive to current in thisdirection. Thus the rectifier G22 constitutes in practice a shortcircuitfor relay ZRI and prevents this relay from energizing at the moment.Relay Cl was energized in the second group selector IIGW and by openingcontact 22c| removes a shortcircuit existing over its winding I and byclosing contact Zlcl connects up this winding in preparation.

The calling subscriber now transmits the second numerical impulse trainfor setting the second group selector IIGW. This influences the impulserelay A in the first group selector IGW. On account of the intermittentrelease of this relay contact 9a is closed and opened a number of timesthereby completing in a corresponding manner the circuit for the impulserelay AI in the second group selector IIGW: earth, contacts Illc and 9a,wiper a of the first group selector IGW, rotary off-normal contact llw,(open after the first rotary step of the second group selector), windingof relay Al, battery and earth. Relay A transmits the impulses thusreceived to the vertical magnet (not shown) of the second group selectorIIGW. After this selector has been set on the desired level it huntsautomatically for a free multiple meter set MZS. When this has beenfound the following testing circuit is established: earth, battery onthe c-lead in the-connecting device arranged beyond the multiple meterset, winding of relay C2 in the multiple meter set MZS, contact 29h,wiper c of the second group selector IIGW, windings I and II of thetesting relay Pl, rectifier G14, contact 250i and earth. The rectifiersGZ3 and GM in the second group selector are arranged in a similar mannerto the rectifiers Gll and GZZ in the first preselector. The rectifierGZ3 is arranged in parallel with winding I of the testing relay PI andis arranged so that it is non-conductive to current fiowing in the samedirection as that in the circuit just described while the rectifier GMis arranged in the opposite sense and thus will transmit current in thisdirection. The latter rectifier accordingly serves to short-circuitrelay ZRZ so that this relay cannot energize for the moment. Relay C2has been energized in the multiple meter set MZS and by closing itscontact 3302 prepares for the energization of relay H.

The calling subscriber now transmits the remaining impulse trains andthus establishes the connection to the desired subscriber by settingfurther connecting devices beyond the multiple meter set.

When the called subscriber replies a circuit which may be closed in anyknown way is completed for relay B in the multiple metering set. Relay Bcloses its contact 32b and thereby connects relay H to the interrupterUl. The interrupter Ul is arranged so that it closes a contact atdefinite intervals of time, for example at intervals of one minute andeach time causes relay H to energize; earth, interrupter Ul, contacts3302 and 32b, winding of relay I-I, battery and earth. Naturally ifnecessary interrupters can be used which close contacts at differentintervals of time. Relay H closes its contact 26h, 30h, and Sih andopens its contact 29h. By closing contact 2671 battery is applied overcontact 2lzr3 and resistance Wil which serves to hold energized devicesconnected to the c-lead in the previous connecting devices, i. e., inthe second group selector. At contact 29h the holding potential appliedin the devices aranged beyond the multiple metering set is disconnectedbut the energization of relay C2 of the multiple metering set and thedevices connected to the c-lead in the following connecting device ismaintained by the connection of earth at contact 39h. By the closing ofcontact 3lh. the following circuit is completed for relay 2R3 in themultiple meter set: earth, contact 31h, winding of relay ZR3, batteryand earth. Through the opening of contact 2 Izr3 the battery potentialconnected over resistance Wil' is disconnected and by the closing ofcontact 2821*3 (without breaking the contact) a source of alternatingcurrent (25 or 50 cycles) is connected over resistance Wis. Thisalternating current flowing over the c-lead operates on the second groupselector IIGW in such a manner that alternate half waves of thisalternating current passes over the rectifier GZ3 while the other halfwaves pass over winding I of relay P! The half waves of this alternatingcurrent in one direction also pass over rectifier G24 while the otherhalf waves pass through the winding of relay ZRZ. The effect of this isthat relay ZR2 in the second group selector IIGW energizes during theconnection of alternating current to the multiple meter set. Thus on theone hand the application of the alternating current serves to maintainthe testing relay Pl energized in the second group selector GW and onthe other hand serves to energize the meter repeating relay ZR2. If thecontact is broken by the interrupter Ul in the multiple metering set,relay H releases and restores the multiple metering set to normalcondition, the source of alternating current being incidentallydisconnected again. Accordingly on account of the short-circuit overrelay ZR2 in the second group selector IIGW produced by the rectifierG14 this relay is caused to deenergize. Each time it energizes relay ZRZopens its contact l8zr2 and closes its contacts W272 and 20zr2. At thelast mentioned contact earth is connected up thereby preventing relay Clfrom releasing. By the closing of contact 1921*;2 a source ofalternating current is connected to wiper c of the first group selectorIGW over resistance Wi5. One half-Wave of the alternating current passesover the rectifier Gll and the other over winding I of relay P. Thusrelay P remains energized during the application of the alternatingcurrent. The rectifier G12 which is conductive to the previous fiow ofcurrent likewise receives I one half-wave of the alternating currentwhile the other passes through the winding of relay ZRI. Relay ZRI isaccordingly energized. It closes its contact Ilzrl thereby giving riseto an increase in the current density over the guarding lead from thepreselector whereby the meter Z of the calling subscriber is advancedone step. On the termination of the application of the alternatingcurrent which is determined by the interrupter Ul in the multiplemetering set MZS the relays ZR3, ZR2, and ZR! are deenergized again,relay ZR3 being deenergized by the opening of contact MK and relays ZRZand ZRI by being short-circuited over the rectifiers G14 and G12.

Thus the normal condition is once more established. In this way themeter Z of the calling station is advanced step by step at intervals oftime determined by the interrupter U I.

At the end of the call all the connecting devices are restored to thenormal position. Since these operations are well known and have nothingto do with the invention a detailed description need not be given.

In Fig. 2 an arrangement is shown by the aid of which a subscriber isenabled to transmit to the exchange operator signals for example. Itwill be assumed that a connection has been established to subscriberT722 over the second.

group selector IIGW, third group selector IIIGW andv the final. selectorLW. This call can for example be set up with the collaboration of. anexchange operator who can also. effect the setting of the switches inquestion. The testing circuit between the second group. selector IIGWand the third group selector IIIGW is as follows: earth, battery,winding of relay C3, contact jg/I, wiperc of the second group selectorIIGW, winding I of relay P2, contact 421:2, rectifier G16, contact 4302and earth. The rectifier G15 is non-conductive; to the current flowingin the above-mentioned circuit so that the entire current passes overwinding 1. of relay P2. Rectifier GL6. on the. other hand is. arrangedin the opposite sense to rectifier G15. and constitutes a shortcircuitfor the winding of relay G 2. so that for the moment this relay cannotenergize. testing circuit between the third group selector IIIGW and thefinal selector LW is as follows: earth, battery, winding I of relay C4,contact 499, wiper c of the third group selector IIIGW, winding; I. ofrelay P3, contact 41123, rectifier G18, contact 4803 and earth. In: thiscircuit only relays C4 and P3 are energized relay GI beingshort-circuited by rectifier G18. The rectifier GZI which is arranged inthe opposite sense to rectifier G18 is non-conductive to the currentflowing in the circuit just mentioned so that the whole of the currentpasses over winding I of.

relay P3.

A relay G having two windings I and. II is arranged in the finalselector. The two windings are arranged difierentially so that relaycannot energize at once when the subscriber T122 takes up his receiver.

If subscriber In! wishes to transmit a signal to the. exchange operatorVB, he operates the key Ta. On account of the connection of earth overkey Taz, the differential relay G. is caused to energize. The closing ofcontact. 5Ig prevents relay C4" from releasing; By the closing ofcontact 50g alternating current is applied tov wiper c' of the thirdgroup selector-IIIGW over resistance will]. On account of the connectionof this alternating currentv relay GI is energized in the thirdv groupselector IIIGW and relay P3 is maintained energized over its winding Iby the half-waves of the alternating current which do not pass throughthe rectifier GZI. (Relay GI is also energized by half-waves ofalternating current which are actually those which do not pass throughrectifier G28.) Relay GI opens its contact 44gI and closes its contact45gI and MigI. Relay C3 is maintained energized at the last mentionedcontact whilst at contact 45gI, alternating current is connected towiper c of the second group selector IIGW over resistance Will, thedirect current potential being disconnected. On account of thisconnection of alternating current relay G2 in the second group selectorIIGW is energized by the alternating half-waves of alternating currentwhich do not pass through rectifier G15. Relay G2 in the second groupselector IIGW is thus energized synchronously with the closing of keyTa. by the subscriber I122 and is deenergized again onthe opening of thekey accordingly. Contact M92 is closed and opened a corresponding numberof times at the The- Here again the release operations are of no specialsignificance so that they will not be described in detail.

By the application of earth at the subscribers station In2, otheroperations can also be effected, for example, another relay could beoperated by relay G2 serving to seize the calling subscriber to form aprotection against false calls.

Fig. 3 shows an arrangement which enables different trafiic directionsto be controlled by the application of the invention. A preselector VWis shown over which a number of traflic directions, for example RI andR11 may be reached. The following circuit is established for the rotarymagnet D2 of the preselector: earth, battery, rotary magnet D2, contactsM05 and 62124, relay interrupter RU2 and earth. The preselector isstepped by means of the relay interrupter until it has. found a freeline in the direction RI. The following testing circuit is then set upfrom earth, battery, winding of relay C6, contact IZdIc, wiper c of thepreselector VW, rectifier G19, contact E'IhI, winding of relay P4, highresistance Wii3, contact H05 and earth. In this circuit the testingrelay P4 and the seizing relay C6 of the connecting device arrangedbeyond the pre-- selector, energize. Relay P4 closes contact 10124 andby short-circuiting the high resistance W113 guards the next connectingdevice which has been seized. At contacts 59114 and 60104 it switchesthrough the speaking leads in the known way. The rectifier G19 isarranged so that it is conductive to the normal testing and guarding'current and thus constitutes a short-circuit for the winding of relay U.The rectifier GZIO is arranged in the opposite sense to rectifier G19 sothat the whole of the current passes over the winding of relay P4.Contact ISdk is only closed when the switching device following thepreselector, for example, the first group selector IGW is raised to adefinite level, for example, level III. If the first preselector IGWarranged beyond the preselector VW is set on one of the levels I'-9 bythe calling subscriber contact I2kd remains closed and there is noswitching over on to the direction RII. The setting of the connectingdevice and the establishment and release of the connection take place inthe known manner and are of no particular interest.

If, however, after the preselector VW has been set on the direction RIan impulse train consisting of 10 impulses is transmitted by the callingsubscriber, contact 12670 is opened in the first group selector andcontact 13cm isclosed. The seizing relay C6 is caused to decnergize bythe opening of contact 'IZdk and the release of the first group selectorwhich occurs shortly afterwards takes place in the known way. On accountof the closing of contact 131270 alternating current is applied to wiperc of the preselector VW over resistance Wz'I I. Relay U in thepreselector VW is accordingly energized by the alternate half waves ofalternating current which do not pass through the rectifier Glil, whilstrelay P4 is similarly held up for the time being. Relay U closes itscontact 6411. and thereby completes the following circuit for relay HI:earth, battery, winding of relay HI, contacts Mu, E505, and earth. RelayHi energizes in this circuit, establishing a locking circuit for itselfby closing its contact 637M and at contacts 3612! short circuits thewinding of relay U so that this relay falls back after a short time. Inaddition relay HI opens its contact 69M and thereby disconnects therectifier Gill] arranged in parallel with the winding of relay P4. Italso opens its contact 61h! and closes contact 6872!, thereby therectifier G1!) which previously was arranged in the opposite sense tothe rectifier GZIIJ is now connected in parallel with the winding ofrelay P4. Since now the rectifier G19 is conductive to those alternatehalf waves which are not transmitted by rectifier Gllll a reversal ofpolarity is effected in the winding of relay P4 which causes it torelease. Relay P4 closes its contact 62104 and thereby completes thecircuit for the rotary magnet D2 of the preselector VW. The preselectoris stepped round by the action of the relay interrupter RUZ and huntsfor a free line in the direction RII. When such a line has been foundthe following testing circuit is established: earth, contact H05, highresistance Wil3, winding of relay Pd, contact 6671.! and in parallelcontact 6871i and rectifier G29, wiper c of the preselector VW, seizingrelay C1 and in parallel thereto rectifier G1! I, resistance W212. andsource of alternating current. In this circuit relay P4 energizes onaccount of the alternate half waves of alternating current which do notpass through the rectifier G19 and this relay by opening its contact62134 brings the preselector to rest. By means or" the short-circuitover the high resistance Wa'iS at contact 10394 the free connectingdevice which has been found in the traffic direction RII is guardedagainst further seizure.

In this case, that is, in the case of calls in the direction RII testingand guarding are effected by means of alternating current.

In this case also the operations for the further setting up of the calland for the release of the call are of no special significance so thatno explanation of these operations will be given.

What is claimed is:

1. In a telephone system, a test circuit over which two differentswitching operations are controlled, a test relay and a control relayincluded in said test circuit, a rectifier shunting each of said relays,one of said rectifiers poled in the opposite direction from the other, asource of direct current, a source of alternating current, means forconnecting either said direct current source or said alternating currentsource to said test circuit, said rectifiers effective to cause saidtest relay to operate to control one of said switching operations whensaid direct current source is connected, and effective to cause saidcontrol relay to operate to control the other of said switchingoperations when alternating current is connected.

2. A system as claimed in claim 1, in which the rectifier shunting thetest relay is non-conductive to direct current flow and the rectifiershunting the control relay is conductive to direct current flow and.thereby short-circuits the control relay.

3. A system as claimed in claim 1, in which the direct current foroperating said test relay is disconnected during the time that said testand said control relays are operated by the alternating current.

4. A system as claimed in claim 1, in which a timing device associatedwith the test circuit of said switch is adapted to momentarily applysaid alternating current to said test circuit at predetermined intervalsand in which a magnet associated with a calling subscribers line circuitis operated responsive to each operation of said control relay.

5. In a telephone system, a plurality of autornatic switches controlledfrom a calling subscribers line for establishing a telephone connection,a test circuit for each of said switches, a test relay and a controlrelay included in each of said test circuits, a source of direct currentfor operating each of said test relays in turn as the call progresses, atiming device associated with the test circuit of the last switch formomentarily applying alternating current thereto at predeterminedintervals to operate the control relay associated with the last switch,means responsive to the operation of any control relay for applyingalternating current to the test circuit of the preceding switch tooperate the associated control relay, line equipment individual to thecalling subscribers line, and means responsive to the operation of thecontrol relay of the first switch for controlling the operation of amagnet associated with said line equipment.

6. ma telephone system, a test circuit over which two differentswitching operations are controlled, a test relay and a control relayincluded in said test circuit, a rectifier shunting each of said relays,one of said rectifiers poled in the opposite direction from the other, asource of direct current, means for connecting said direct currentsource to said test circuit to operate said test relay, means responsiveto the operation of said test relay for controlling one of saidswitching operations, said control relay shunted by its associatedrectifier when said direct current is connected to said test circuit, asource of alternating current, means for connecting said alternatingcurrent source to said test circuit to operate said control relay, andmeans responsive to the operation of said control relay for controllingthe other of said switching operations, each rec tifier shunting itsassociated relay on one-half of each cycle of alternating current andpreventing the shunting of its associated relay on the other half ofeach cycle of alternating current. 5

7. In combination, a first and second relay in a series circuit, arectifier associated with each of said relays for permitting current ofone polarity but not of the other to fiow through said first relay andfor permitting current of the second polarity but not of the first toflow through said second relay, means for applying direct current of onepolarity to said series circuit to energize said first relay, means forapplying alternating current to said series circuit to maintain saidfirst relay energized and to ener gize said second relay; meansresponsive to the energization of said second relay for releasing bothof said relays and for altering said series circuit so that therectifier associated with said first relay is disconnected therefrom,the rectifier associated with said second relay is disconnectedtherefrom and associated with said first relay, and said second relay isshunted to prevent energizing; and means for again applying alternatingcurrent to said altered circuit t again energize said first relay.

8. In combination, two relays in a series cir cuit, a rectifierassociated with each of said relays for permitting current of onepolarity but not of the other to flow through one relay winding and forpermitting current of the second polarity but not of the first to flowthrough the second relay winding, means for applying direct current ofone polarity to said series circuit to energize one of said relays,means for applying alternating current to said series circuit tomaintain said one relay energized and to energize the other of saidrelays, means responsive to the operation of the other of saidrelaysforreleasing both of said relays and for altering said series circuit, andmeans for again applying alternating current to said altered seriescircuit to again energize the said one of said relays previouslyenergized by direct current.

9. In a circuit arrangement, an automatic switch adapted to extend aconnection therethrough, a test relay, a control relay, a rectifiershunting each one of said relays, a test circuit for said switchincluding said test relay and said control relay, means for applyingdirect current to said test circuit to operate said test relay, saidrectifiers being oppositely poled so that said test relay operates andsaid control relay is shunted when said direct current is connected tosaid test circuit, means for applying alternating current to said testcircuit to maintain said test relay energized and to energize saidcontrol relay, said rectifiers effective to prevent the release of saidrelays on alternate half-cycles of alternating current.

10. In combination, an automatic switch, meansfor extending a connectiontherethrough, said switch having a test relay and a control relay, arectifier bridging each of said relays, a source of direct current, asource of alternating current, means for connecting said source ofdirect current to said relays, said rectifiers associated with saidrelays so poled that application of direct current thereto causes onlythe test relay to operate, means for changing said connecting means fromsaid source of direct current to said source of alternating current tomaintain said test relay energized and to cause said control relay tooperate.

11. In an automatic circuit arrangement, an automatic switch, a testcircuit associated therewith for controlling different switchingoperations thereof, said circuit including a test relay, a controlrelay, and shunting rectifiers for each of said relays, a source ofdirect current connected to the test circuit for operating said testrelay to control a switching operation, the rectifier shunting said testrelay poled so that it is non-conductive to the direct current and therectifier shunting the control relay poled so that it is conductive todirect current and short circuits said control relay, a source ofalternating current, means for disconnecting said source of directcurrent and for connecting said source of alternating current, saidalternating current maintaining said test relay energized and completingan energizing circuit for said control relay, and means responsive tothe operation of said control relay to control a second switchingoperation.

12. An automatic telephone system as claimed in claim 11, in which saidsecond switching operation causes the release of said test and controlrelays and said test relay then reoperates responsive to a secondconnection to said alternating current source to control a thirdswitching operation.

HERBERT T6PFER.

